1. Technical Field
The present disclosure relates to display devices. In particular, the present disclosure relates to a display device provided with a displaying unit at a front surface of a flexible substrate having a rigid substrate at a rear surface thereof, and to a method for manufacturing the display device.
2. Description of the Related Art
As portable information terminals and the like are becoming more and more popular in recent years, there are strong demands for thickness reduction, weight reduction, and improved durability in display devices equipped in these terminals. In addition to these demands, there is recently also an increasing demand for display devices with high flexibility. In order to meet such demands, manufacturing methods for display devices have been studied.
For example, in order to achieve thickness reduction, weight reduction, and flexibility of a display device, there has been studied a display-device manufacturing method that involves forming, for example, a display element unit on a glass substrate and subsequently reducing the thickness of the entire glass substrate by grinding the glass substrate. On the other hand, in order to achieve durability and flexibility of a display device, there have been studied a configuration that uses a resin substrate and a thin glass substrate and a configuration that uses a resin substrate alone. PCT International Publication No. 2002/084739 discloses a display-device manufacturing method that involves forming a thin-film transistor on a glass substrate, removing the entire glass substrate, and then transferring the thin-film transistor onto a resin substrate. Japanese Patent No. 4870156 discloses a display-device manufacturing method that involves forming a resin substrate on a glass substrate, forming, for example, a display element unit on the resin substrate, and then separating the resin substrate from the glass substrate.
In general, a display device includes a substrate, a display element unit provided on the substrate, and a driving integrated circuit (IC) electrically connected to the display element unit. The display element unit is provided with, for example, a thin-film transistor therein. With this configuration, when a video signal from an external device is input to the display element unit via the driving IC, the thin-film transistor is driven in correspondence with the video signal, so that the display device displays a video picture.
In order to electrically connect the display element unit and the driving IC to each other, there is a method of directly connecting the driving IC to the wire electrically connected to the display element unit and a method of connecting via a flexible printed circuit (referred to as “FPC” hereinafter). When using the direct connection method, the driving IC is electrically connected to the wire, which extends from the display element unit. When using the via-FPC connection method, an output terminal of the driving IC is mounted in the FPC such that the output terminal of the driving IC is disposed on the FPC and is electrically connected to the wire provided in the FPC. Then, an output terminal of the FPC is electrically connected to the wire, which extends from the display element unit, on the substrate. Either of the two connection methods uses an anisotropic conductive film (referred to as “ACF” hereinafter). By thermo-compression-bonding the two terminals connected to each other via the ACF, the two terminals can be electrically connected to each other.